The invention relates, in general, to refrigeration and, more particularly, to a new and useful method and device for measuring the required cooling capacity of a cold space.
Refrigerating machinery is used for a variety of purposes such as for storing of foodstuffs in industry, manufacture, trade, distribution and households, for air conditioning, in the medical science for tissue transplants, for storing of blood and blood plasma, in the chemical industry for process controlling and also for heating purposes in connection with heat pumps.
Because of the numerous areas of applicability, naturally, a multitude of apparatuses for achieving temperatures below the ambient temperature exist. The apparatuses are also characterized by a certain uniqueness, a typical example being the cold-storage rooms in connection with kitchens of row-style and single-family houses: hardly two identical self-made cold-storage rooms exist.
For the above reasons it is mostly necessary, when dimensioning the apparatuses to use approximate formulae and estimations, the accuracy of measurement of which is not especially good. Therefore the machinery is often over-dimensioned to be on the safe side, so that the refrigerating capacity will be sufficient.
In connection with factory-built products the refrigeration demand can usually be determined in the factory laboratory or in pilot cold rooms with the required accuracy. This applies especially to refrigerators, coolers and household freezers and to some extent also cold-storage rooms. In case of larger units which are either completely or partly built or assembled at their final location site the circumstances are somewhat different: the units are not necessarily assembled in the same way as under the supervised conditions in the factory, and especially the insulating of the constructions with their moisture proof vapour barriers, is often construction-wise and overly complicated procedure. Therefore the required cooling capacity normally is also greater than in a factory made unit of the same size.
Quite a different category of refrigeration units are used in connection with the building of cold spaces for cold storage units. These conventionally are built completely--except for the door--on their final location site, and wherefrom often a part of the insulation is left out, that is to give a sufficient room height; this method is commonly used i.a. in refrigerated domestic storage cellars, where the floor insulation is often completely omitted. Also, in supermarkets, the insulating floor elements in element built cold spaces are sometimes left out in order to level the interior floor with its surrounding. This is of importance when moving goods in carriers into and out from the cold storage room.
Because of the aforementioned, the required cooling capacities of many cold spaces as well as the refrigeration capacities of the refrigerating machinery therefor, are only approximately known.